Organic electroluminescent devices (OELs) include layers of organic materials, at least one of which can conduct a charge. Examples of organic electroluminescent devices include organic light emitting diodes (OLEDs). Specific OEL devices, sometimes referred to as lamps, are desirable for use in electronic media because of their thin profile, low weight, and low driving voltage. OEL devices have potential use in applications such as, for example, lighting applications, backlighting of graphics, pixelated displays, and large emissive graphics.
OEL devices typically include an organic light emitter layer and optionally one or more charge transport layers, all of which are sandwiched between two electrodes: a cathode and an anode. Charge carriers, electrons and holes, are injected from the cathode and anode, respectively. Electrons are negatively charged atomic particles and holes are vacant electron energy states that behave as though they are positively charged particles. The charge carriers migrate to the emitter layer, where they combine to emit light.
This basic OEL device structure can be modified to improve or enhance one or more electrical, chemical, or physical properties of the device. Such modification can include the addition or modification of one or more of the basic layers.